Figure 3. Effect of Geld on [Ca²⁺]_i in human sperm during capacitation.

Sperm loaded with 10 µM Fluo-3 AM were washed twice with human tubal fluid (HTF) to remove free Fluo-3 AM. After incubation at 37°C for 20 min, Fluo-3 AM-loaded sperm aliquots (10⁶ cells/ml) were incubated with dimethyl sulfoxide (DMSO, 0.3%, v/v) as the vehicle control (star), 2.5 µM progesterone (P4, circle), 20 µM geldanamycin (Geld, triangle), or 20 µM Geld and 2.5 µM P4 (square). Treated sperm were then analyzed as described in Materials and Methods. The results are expressed as means ±SEM (n = 6); *P<0.05, compared to vehicle control.